Proteases decode the extracellular matrix cryptome

Protein-based nanoparticles for therapeutic nucleic acid delivery

To realize the full potential of emerging nucleic acid therapies, there is a need for effective delivery agents to transport cargo to cells of interest. Protein materials exhibit several unique properties, including biodegradability, biocompatibility, ease of functionalization via recombinant and chemical modifications, among other features, which establish a promising basis for therapeutic nucleic acid delivery systems. In this review, we highlight progress made in the use of non-viral protein-based nanoparticles for nucleic acid delivery in vitro and in vivo, while elaborating on key physicochemical properties that have enabled the use of these materials for nanoparticle formulation and drug delivery. To conclude, we comment on the prospects and unresolved challenges associated with the translation of protein-based nucleic acid delivery systems for therapeutic applications.

Copper Forms a PPII Helix-Like Structure with the Catalytic Domains of Bacterial Zinc Metalloproteases

The rapid spread of antibiotic-resistant bacteria continuously raises concerns about the future ineffectiveness of current antimicrobial treatments against infectious diseases. To address this problem, new therapeutic strategies and antimicrobial drugs with unique modes of action are urgently needed. Inhibition of metalloproteases, bacterial virulence factors, is a promising target for the development of antibacterial treatments. In this study, the interaction among Zn(II), Cu(II), and the metal-binding domains of two metalloproteases, AprA (Pseudomonas aureginosa) and CpaA (Acinetobacter baumanii), was investigated. The objective was to determine the coordination sphere of Zn(II) with a peptide model of two zinc-dependent metalloproteases. Additionally, the study explored the formation of Cu(II) complexes with the domains, as Cu(II) has been shown to inhibit metalloproteases. The third aim was to understand the role of nonbinding amino acids in stabilizing the metal complexes formed by these proteases. This work identified specific coordination patterns (HExxHxxxxxH) for both Zn(II) and Cu(II) complexes, with AprA and CpaA exhibiting a higher affinity for Cu(II) compared to Zn(II). The study also found that the CpaA domain has greater stability for both Zn(II) and Cu(II) complexes compared to AprA. The nonbinding amino acids of CpaA surrounding the metal ion contribute to the increased thermodynamic stability of the metal-peptide complex through various intramolecular interactions. These interactions can also influence the secondary structures of the peptides. The presence of certain amino acids, such as tyrosine, arginine, and glutamic acid, and their interactions contribute to the stability and, only in the case of Cu(II) complexes, the formation of a rare protein structure called a left-handed polyproline II helix (PPII), which is known to play a role in the stability and function of various proteins. These findings provide valuable insights into the coordination chemistry of bacterial metalloproteases and expand our understanding of potential mechanisms for inhibiting these enzymes.

New Biotinylated GHK and Related Copper(II) Complex: Antioxidant and Antiglycant Properties In Vitro against Neurodegenerative Disorders

Neurodegenerative diseases affect millions of people worldwide. The failure of the enzymatic degradation, the oxidative stress, the dyshomeostasis of metal ions, among many other biochemical events, might trigger the pathological route, but the onset of these pathologies is unknown. Multi-target and multifunctional molecules could address several biomolecular issues of the pathologies. The tripeptide GHK, a bioactive fragment of several proteins, and the related copper(II) complex have been largely used for many purposes, from cosmetic to therapeutic applications. GHK derivatives were synthesized to increase the peptide stability and improve the target delivery. Herein we report the synthesis of a new biotin-GHK conjugate (BioGHK) through orthogonal reactions. BioGHK is still capable of coordinating copper(II), as observed by spectroscopic and spectrometric measurements. The spectroscopic monitoring of the copper-induced ascorbate oxidation was used to measure the antioxidant activity Cu(II)-BioGHK complex, whereas antiglycant activity of the ligand towards harmful reactive species was investigated using MALDI-TOF. The affinity of BioGHK for streptavidin was evaluated using a spectrophotometric assay and compared to that of biotin. Finally, the antiaggregant activity towards amyloid-β was evaluated using a turn-on fluorescent dye. BioGHK could treat and/or prevent several adverse biochemical reactions that characterize neurodegenerative disorders, such as Alzheimer's disease.

Engineering of extracellular matrix from human iPSC-mesenchymal progenitors to enhance osteogenic capacity of human bone marrow stromal cells independent of their age

Regeneration of bone defects is often limited due to compromised bone tissue physiology. Previous studies suggest that engineered extracellular matrices enhance the regenerative capacity of mesenchymal stromal cells. In this study, we used human-induced pluripotent stem cells, a scalable source of young mesenchymal progenitors (hiPSC-MPs), to generate extracellular matrix (iECM) and test its effects on the osteogenic capacity of human bone-marrow mesenchymal stromal cells (BMSCs). iECM was deposited as a layer on cell culture dishes and into three-dimensional (3D) silk-based spongy scaffolds. After decellularization, iECM maintained inherent structural proteins including collagens, fibronectin and laminin, and contained minimal residual DNA. Young adult and aged BMSCs cultured on the iECM layer in osteogenic medium exhibited a significant increase in proliferation, osteogenic marker expression, and mineralization as compared to tissue culture plastic. With BMSCs from aged donors, matrix mineralization was only detected when cultured on iECM, but not on tissue culture plastic. When cultured in 3D iECM/silk scaffolds, BMSCs exhibited significantly increased osteogenic gene expression levels and bone matrix deposition. iECM layer showed a similar enhancement of aged BMSC proliferation, osteogenic gene expression, and mineralization compared with extracellular matrix layers derived from young adult or aged BMSCs. However, iECM increased osteogenic differentiation and decreased adipocyte formation compared with single protein substrates including collagen and fibronectin. Together, our data suggest that the microenvironment comprised of iECM can enhance the osteogenic activity of BMSCs, providing a bioactive and scalable biomaterial strategy for enhancing bone regeneration in patients with delayed or failed bone healing.

The Extracellular Matrix: Its Composition, Function, Remodeling, and Role in Tumorigenesis

The extracellular matrix (ECM) is a ubiquitous member of the body and is key to the maintenance of tissue and organ integrity. Initially thought to be a bystander in many cellular processes, the extracellular matrix has been shown to have diverse components that regulate and activate many cellular processes and ultimately influence cell phenotype. Importantly, the ECM's composition, architecture, and stiffness/elasticity influence cellular phenotypes. Under normal conditions and during development, the synthesized ECM constantly undergoes degradation and remodeling processes via the action of matrix proteases that maintain tissue homeostasis. In many pathological conditions including fibrosis and cancer, ECM synthesis, remodeling, and degradation is dysregulated, causing its integrity to be altered. Both physical and chemical cues from the ECM are sensed via receptors including integrins and play key roles in driving cellular proliferation and differentiation and in the progression of various diseases such as cancers. Advances in 'omics' technologies have seen an increase in studies focusing on bidirectional cell-matrix interactions, and here, we highlight the emerging knowledge on the role played by the ECM during normal development and in pathological conditions. This review summarizes current ECM-targeted therapies that can modify ECM tumors to overcome drug resistance and better cancer treatment.

10 years of extracellular matrix proteomics: Accomplishments, challenges, and future perspectives

The extracellular matrix (ECM) is a complex assembly of hundreds of proteins forming the architectural scaffold of multicellular organisms. In addition to its structural role, the ECM conveys signals orchestrating cellular phenotypes. Alterations of ECM composition, abundance, structure, or mechanics, have been linked to diseases and disorders affecting all physiological systems, including fibrosis and cancer. Deciphering the protein composition of the ECM and how it changes in pathophysiological contexts is thus the first step toward understanding the roles of the ECM in health and disease and toward the development of therapeutic strategies to correct disease-causing ECM alterations. Potentially, the ECM also represents a vast, yet untapped reservoir of disease biomarkers. ECM proteins are characterized by unique biochemical properties that have hindered their study: they are large, heavily and uniquely post-translationally modified, and highly insoluble. Overcoming these challenges, we and others have devised mass-spectrometry-based proteomic approaches to define the ECM composition, or "matrisome", of tissues. This review provides a historical overview of ECM proteomics research and presents the latest advances that now allow the profiling of the ECM of healthy and diseased tissues. The second part highlights recent examples illustrating how ECM proteomics has emerged as a powerful discovery pipeline to identify prognostic cancer biomarkers. The third part discusses remaining challenges limiting our ability to translate findings to clinical application and proposes approaches to overcome them. Last, the review introduces readers to resources available to facilitate the interpretation of ECM proteomics datasets. The ECM was once thought to be impenetrable. MS-based proteomics has proven to be a powerful tool to decode the ECM. In light of the progress made over the past decade, there are reasons to believe that the in-depth exploration of the matrisome is within reach and that we may soon witness the first translational application of ECM proteomics.

Building, Visualizing, and Analyzing Glycosaminoglycan-Protein Interaction Networks

This chapter describes how to generate, visualize, and analyze interaction networks of glycosaminoglycans (GAGs), which are linear polyanionic polysaccharides mostly located at the cell surface and in the extracellular matrix. The protocol is divided into three major steps: (1) the collection of GAG-mediated interaction data, (2) the visualization of GAG interaction networks, and (3) the computational enrichment analyses of these networks to identify their overrepresented features (e.g., protein domains, location, molecular functions, and biological pathways) compared to a reference proteome. These analyses are critical to interpret GAG interactomic datasets, decipher their specificities and functions, and ultimately identify GAG-protein interactions to target for therapeutic purpose.

Focus on the tumor microenvironment: A seedbed for neuroendocrine prostate cancer

The tumor microenvironment (TME) is a microecology consisting of tumor and mesenchymal cells and extracellular matrices. The TME plays important regulatory roles in tumor proliferation, invasion, metastasis, and differentiation. Neuroendocrine differentiation (NED) is a mechanism by which castration resistance develops in advanced prostate cancer (PCa). NED is induced after androgen deprivation therapy and neuroendocrine prostate cancer (NEPC) is established finally. NEPC has poor prognosis and short overall survival and is a major cause of death in patients with PCa. Both the cellular and non-cellular components of the TME regulate and induce NEPC formation through various pathways. Insights into the roles of the TME in NEPC evolution, growth, and progression have increased over the past few years. These novel insights will help refine the NEPC formation model and lay the foundation for the discovery of new NEPC therapies targeting the TME.

Comparative Genomics Reveal the Animal-Associated Features of the Acanthopleuribacteraceae Bacteria, and Description of Sulfidibacter corallicola gen. nov., sp., nov

Members of the phylum Acidobacteria are ubiquitous in various environments. Soil acidobacteria have been reported to present a variety of strategies for their success in terrestrial environments. However, owing to lack of pure culture, information on animal-associated acidobacteria are limited, except for those obtained from 16S rRNA genes. To date, only two acidobacteria have been isolated from animals, namely strain M133^T obtained from coral Porites lutea and Acanthopleuribacter pedis KCTC 12899^T isolated from chiton. Genomics and physiological characteristics of strain M133^T and A. pedis KCTC 12899^T were compared with 19 other isolates (one strain from each genus) in the phylum Acidobacteria. The results revealed that strain M133^T represents a new species in a new genus in the family Acanthopleuribacteraceae. To date, these two Acanthopleuribacteraceae isolates have the largest genomes (10.85–11.79 Mb) in the phylum Acidobacteria. Horizontal gene transfer and gene duplication influenced the structure and plasticity of these large genomes. Dissimilatory nitrate reduction and abundant secondary metabolite biosynthetic gene clusters (including eicosapentaenoic acid de novo biosynthesis) are two distinct features of the Acanthopleuribacteraceae bacteria in the phylum Acidobacteria. The absence of glycoside hydrolases involved in plant polysaccharide degradation and presence of animal disease-related peptidases indicate that these bacteria have evolved to adapt to the animal hosts. In addition to low- and high-affinity respiratory oxygen reductases, enzymes for nitrate to nitrogen, and sulfhydrogenase were also detected in strain M133^T, suggesting the capacity and flexibility to grow in aerobic and anaerobic environments. This study highlighted the differences in genome structure, carbohydrate and protein utilization, respiration, and secondary metabolism between animal-associated acidobacteria and other acidobacteria, especially the soil acidobacteria, displaying flexibility and versatility of the animal-associated acidobacteria in environmental adaption.

Comparison of extracellular matrix enrichment protocols for the improved characterization of the skin matrisome by mass spectrometry

A striking feature of skin organization is that the extracellular matrix (ECM) occupies a larger volume than the cells. Skin ECM also directly contributes to aging and most cutaneous diseases. In recent years, specific ECM enrichment protocols combined with in silico approaches allowed the proteomic description of the matrisome of various organs and tumor samples. Nevertheless, the skin matrisome remains under-studied and protocols allowing the efficient recovery of the diverse ECM found in skin are still to be described. Here, we compared four protocols allowing the enrichment of ECM proteins from adult mouse back skin and found that all protocols led to a significant enrichment (up to 65%) of matrisome proteins when compared to total skin lysates. The protocols based on decellularization and solubility profiling gave the best results in terms of numbers of proteins identified and confirmed that skin matrisome proteins exhibit very diverse solubility and abundance profiles. We also report the first description of the skin matrisome of healthy adult mice that includes 236 proteins comprising 95 core matrisome proteins and 141 associated matrisome proteins. These results provide a reliable basis for future characterizations of skin ECM proteins and their dysregulations in disease-specific contexts. SIGNIFICANCE: Extracellular matrix proteins are key players in skin physiopathology and have been involved in several diseases such as genetic disorders, wound healing defects, scleroderma and skin carcinoma. However, skin ECM proteins are numerous, diverse and challenging to analyze by mass spectrometry due to the multiplicity of their post-translational modifications and to the heterogeneity of their solubility profiles. Here, we performed the thorough evaluation of four ECM enrichment protocols compatible with the proteomic analysis of mouse back skin and provide the first description of the adult mouse skin matrisome in homeostasis conditions. Our work will greatly facilitate the future characterization of skin ECM alterations in preclinical mouse models and will inspire new optimizations to analyze the skin matrisome of other species and of human clinical samples.

Extracellular Metalloproteinases in the Plasticity of Excitatory and Inhibitory Synapses

Long-term synaptic plasticity is shaped by the controlled reorganization of the synaptic proteome. A key component of this process is local proteolysis performed by the family of extracellular matrix metalloproteinases (MMPs). In recent years, considerable progress was achieved in identifying extracellular proteases involved in neuroplasticity phenomena and their protein substrates. Perisynaptic metalloproteinases regulate plastic changes at synapses through the processing of extracellular and membrane proteins. MMP9 was found to play a crucial role in excitatory synapses by controlling the NMDA-dependent LTP component. In addition, MMP3 regulates the L-type calcium channel-dependent form of LTP as well as the plasticity of neuronal excitability. Both MMP9 and MMP3 were implicated in memory and learning. Moreover, altered expression or mutations of different MMPs are associated with learning deficits and psychiatric disorders, including schizophrenia, addiction, or stress response. Contrary to excitatory drive, the investigation into the role of extracellular proteolysis in inhibitory synapses is only just beginning. Herein, we review the principal mechanisms of MMP involvement in the plasticity of excitatory transmission and the recently discovered role of proteolysis in inhibitory synapses. We discuss how different matrix metalloproteinases shape dynamics and turnover of synaptic adhesome and signal transduction pathways in neurons. Finally, we discuss future challenges in exploring synapse- and plasticity-specific functions of different metalloproteinases.

Inhibition of bacterial and human zinc-metalloproteases by bisphosphonate- and catechol-containing compounds

Compounds containg catechol or bisphosphonate were tested as inhibitors of the zinc metalloproteases, thermolysin (TLN), pseudolysin (PLN) and aureolysin (ALN) which are bacterial virulence factors, and the human matrix metalloproteases MMP-9 and -14. Inhibition of virulence is a putative strategy in the development of antibacterial drugs, but the inhibitors should not interfere with human enzymes. Docking indicated that the inhibitors bound MMP-9 and MMP-14 with the phenyl, biphenyl, chlorophenyl, nitrophenyl or methoxyphenyl ringsystem in the S₁'-subpocket, while these ringsystems entered the S₂'- or S₁ -subpockets or a region involving amino acids in the S₁'- and S₂'-subpockets of the bacterial enzymes. An arginine conserved among the bacterial enzymes seemed to hinder entrance deeply into the S₁'-subpocket. Only the bisphosphonate containing compound RC2 bound stronger to PLN and TLN than to MMP-9 and MMP-14. Docking indicated that the reason was that the conserved arginine (R203 in TLN and R198 in PLN) interacts with phosphate groups of RC2.

Salivary KLK5 and uPA are potential biomarkers for malignant transformation of OLK and OLP

BACKGROUND

Oral squamous cell carcinoma (OSCC) usually originates from oral potentially malignant disorders (OPMD), such as oral leukoplakia (OLK) and oral lichen planus (OLP). Identifying biomarkers for the early diagnosis and evaluation of malignant transformation in OPMD could improve the survival rate of OSCC patients.

OBJECTIVE

The present study aimed to screen for potential salivary biomarkers for evaluating the malignant transformation of OPMD.

METHODS

Salivary proteases from OLK and OSCC patients or healthy donors and proteases in cultural medium from DOK and Cal-27 cells were detected with a human protease array kit. The concentrations of the salivary Kallikrein 5 (KLK5) and urokinase-type plasminogen activator (uPA) proteases were measured by ELISA. Receiver operating characteristics (ROC) to determine the potential value of these proteases in clinical diagnosis were calculated using SPSS software. Immunohistochemistry was used to detect the KLK5 and uPA expression in the oral organizations.

RESULTS

The salivary protease spectrum was different among patients with OLK and OSCC and healthy donors. KLK5 and uPA levels in saliva tended to increase as the disease progressed (healthy < OPMD [OLK and OLP] < OSCC). ROC curves showed the optimum diagnostic cutoffs for KLK5 as a biomarker for OLK, OLP, and OSCC were 5.97, 6.03, and 9.45 pg/mL, respectively, while the cutoffs for uPA were 17.19, 17.26, and 20.96 pg/mL. Their combined analysis showed a higher sensitivity for the differential diagnosis of disease. Furthermore, higher levels of KLK5 and uPA were observed in OSCC tissues than in OLK and OLP.

CONCLUSIONS

Salivary KLK5 and uPA are potential biomarkers for evaluating OLK and OLP malignant transformation and early diagnosis of OSCC.

The Charming World of the Extracellular Matrix: A Dynamic and Protective Network of the Intestinal Wall

The intestinal extracellular matrix (ECM) represents a complex network of proteins that not only forms a support structure for resident cells but also interacts closely with them by modulating their phenotypes and functions. More than 300 molecules have been identified, each of them with unique biochemical properties and exclusive biological functions. ECM components not only provide a scaffold for the tissue but also afford tensile strength and limit overstretch of the organ. The ECM holds water, ensures suitable hydration of the tissue, and participates in a selective barrier to the external environment. ECM-to-cells interaction is crucial for morphogenesis and cell differentiation, proliferation, and apoptosis. The ECM is a dynamic and multifunctional structure. The ECM is constantly renewed and remodeled by coordinated action among ECM-producing cells, degrading enzymes, and their specific inhibitors. During this process, several growth factors are released in the ECM, and they, in turn, modulate the deposition of new ECM. In this review, we describe the main components and functions of intestinal ECM and we discuss their role in maintaining the structure and function of the intestinal barrier. Achieving complete knowledge of the ECM world is an important goal to understand the mechanisms leading to the onset and the progression of several intestinal diseases related to alterations in ECM remodeling.

The matrix in cancer

The extracellular matrix is a fundamental, core component of all tissues and organs, and is essential for the existence of multicellular organisms. From the earliest stages of organism development until death, it regulates and fine-tunes every cellular process in the body. In cancer, the extracellular matrix is altered at the biochemical, biomechanical, architectural and topographical levels, and recent years have seen an exponential increase in the study and recognition of the importance of the matrix in solid tumours. Coupled with the advancement of new technologies to study various elements of the matrix and cell-matrix interactions, we are also beginning to see the deployment of matrix-centric, stromal targeting cancer therapies. This Review touches on many of the facets of matrix biology in solid cancers, including breast, pancreatic and lung cancer, with the aim of highlighting some of the emerging interactions of the matrix and influences that the matrix has on tumour onset, progression and metastatic dissemination, before summarizing the ongoing work in the field aimed at developing therapies to co-target the matrix in cancer and cancer metastasis.

Comprehensive Analysis of Survival-Related lncRNAs, miRNAs, and mRNAs Forming a Competing Endogenous RNA Network in Gastric Cancer

To analyze and construct a survival-related endogenous RNA (ceRNA) network in gastric cancer (GC) with lymph node metastasis, we obtained expression profiles of long non-coding RNAs (lncRNAs), mRNAs, and microRNAs (miRNAs) in GC from The Cancer Genome Atlas database. The edgeR package was used to screen differentially expressed lncRNAs, mRNAs, and miRNAs between GC patients with lymphatic metastasis and those without lymphatic metastasis. Then, we used univariate Cox regression analysis to identify survival-related differentially expressed RNAs. In addition, we used multivariate Cox regression analysis to screen lncRNAs, miRNAs, and mRNAs for use in the prognostic prediction models. The results showed that 2,247 lncRNAs, 155 miRNAs, and 1,253 mRNAs were differentially expressed between the two patient groups. Using univariate Cox regression analysis, we found that 395 lncRNAs, eight miRNAs, and 180 mRNAs were significantly related to the survival time of GC patients. We next created a survival-related network consisting of 59 lncRNAs, seven miRNAs, and 36 mRNAs. In addition, we identified eight RNAs associated with prognosis by multivariate Cox regression analysis, comprising three lncRNAs (AC094104.2, AC010457.1, and AC091832.1), two miRNAs (miR-653-5p and miR-3923), and three mRNAs (C5orf46, EPHA8, and HPR); these were used to construct the prognostic prediction models, and their risk scores could be used to assess GC patients' prognosis. In conclusion, this study provides new insights into ceRNA networks in GC and the screening of prognostic biomarkers for GC.

A guide to the composition and functions of the extracellular matrix

Extracellular matrix (ECM) is a dynamic 3-dimensional network of macromolecules that provides structural support for the cells and tissues. Accumulated knowledge clearly demonstrated over the last decade that ECM plays key regulatory roles since it orchestrates cell signaling, functions, properties and morphology. Extracellularly secreted as well as cell-bound factors are among the major members of the ECM family. Proteins/glycoproteins, such as collagens, elastin, laminins and tenascins, proteoglycans and glycosaminoglycans, hyaluronan, and their cell receptors such as CD44 and integrins, responsible for cell adhesion, comprise a well-organized functional network with significant roles in health and disease. On the other hand, enzymes such as matrix metalloproteinases and specific glycosidases including heparanase and hyaluronidases contribute to matrix remodeling and affect human health. Several cell processes and functions, among them cell proliferation and survival, migration, differentiation, autophagy, angiogenesis, and immunity regulation are affected by certain matrix components. Structural alterations have been also well associated with disease progression. This guide on the composition and functions of the ECM gives a broad overview of the matrisome, the major ECM macromolecules, and their interaction networks within the ECM and with the cell surface, summarizes their main structural features and their roles in tissue organization and cell functions, and emphasizes the importance of specific ECM constituents in disease development and progression as well as the advances in molecular targeting of ECM to design new therapeutic strategies.

Enzymatic preparation of Crassostrea oyster peptides and their promoting effect on male hormone production

ETHNOPHARMACOLOGICAL RELEVANCE

Crassostrea gigas Thunberg and other oysters have been traditionally used in China as folk remedies to invigorate the kidney and as natural aphrodisiacs to combat male impotence.

AIM OF THE STUDY

Erectile dysfunction (ED) has become a major health problem for the global ageing population. The aim of this study is therefore to evaluate the effect of peptide-rich preparations from C. gigas oysters on ED and related conditions as increasing evidence suggests that peptides are important bioactive components of marine remedies and seafood.

MATERIALS AND METHODS

Crassostrea oyster peptide (COP) preparations COP1, COP2 and COP3 were obtained from C. gigas oysters by trypsin, papain or sequential trypsin-papain digestion, respectively. The contents of testosterone, cyclic adenosine monophosphate (cAMP) and nitric oxide (NO) and the activity of nitric oxide synthase (NOS) in mice and/or cells were measured by enzyme-linked immunosorbent assays. Real-time PCR was used to assess the expression of genes associated with sex hormone secretion pathways. The model animal Caenorhabditis elegans was also used to analyze the gene expression of a conserved steroidogenic enzyme. In silico analysis of constituent peptides was performed using bioinformatic tools based on public databases.

RESULTS

The peptide-rich preparation COP3, in which >95% peptides were <3000 Da, was found to increase the contents of male mouse serum testosterone and cAMP, both of which are known to play important roles in erectile function, and to increase the activity of mouse penile NOS, which is closely associated with ED. Further investigation using mouse Leydig-derived TM3 cells demonstrates that COP3 was able to stimulate the production of testosterone as well as NO, a pivotal mediator of penile erection. Real-time PCR analysis reveals that COP3 up-regulated the expression of Areg and Acvr2b, the genes known to promote sex hormone secretion, but not Fst, a gene involved in suppressing follicle-stimulating hormone release. Furthermore, COP3 was also shown to up-regulate the expression of let-767, a well-conserved C. elegans gene encoding a protein homologous to human 17-β-hydroxysteroid dehydrogenases. Preliminary bioinformatic analysis using the peptide sequences in COP3 cryptome identified 19 prospective motifs, each of which occurred in more than 10 peptides.

CONCLUSIONS

In this paper, Crassostrea oyster peptides were prepared by enzymatic hydrolysis and were found for the first time to increase ED-associated biochemical as well as molecular biology parameters. These results may help to explain the ethnopharmacological use of oysters and provide an important insight into the potentials of oyster peptides in overcoming ED-related health issues.

Matrisome Provides a Supportive Microenvironment for Skin Functions of Diverse Species

A biomaterial scaffold is a promising tool employed to drive tissue regeneration. This technology has been successfully applied in human tissue rebuilding, particularly for the skin. Meanwhile, there is still room for further improvement, such as maintaining sufficient functionality of a biomaterial scaffold. Here, we developed a new decellularization method to generate a complete anatomical skin biomatrix scaffold with a preserved extracellular matrix (ECM) architecture. We performed proteomic and bioinformatic analyses of the skin scaffold maps of humans, pigs, and rats and systematically analyzed the interaction between ECM proteins and different cell types in the skin microenvironment. These interactions served to quantify the structure and function of the skin's Matrisome comprising core ECM components and ECM-associated soluble signaling molecules required for the regulation of epidermal development. We primarily found that the properties of the skin ECM were species-specific. For example, the composition and function of the ECM of the human skin were more similar to those of pigs compared with those of rats. However, the skin ECM of the pig was significantly deficient in its enzyme systems and immune regulatory factors compared with that of humans. These findings provide a new understanding of the role of the skin ECM niche as well as an attractive strategy that can apply tissue engineering principles to skin biomatrix scaffold materials, which promises to accelerate and enhance tissue regeneration.

Extracellular matrix-derived peptides in tissue remodeling and fibrosis

Alterations in the composition of the extracellular matrix (ECM) critically regulate the cellular responses in tissue repair, remodeling, and fibrosis. After injury, proteolytic degradation of ECM generates bioactive ECM fragments, named matricryptins, exposing cryptic sites with actions distinct from the parent molecule. Matricryptins contribute to the regulation of inflammatory, reparative, and fibrogenic cascades through effects on several different cell types both in acute and chronic settings. Fibroblasts play a major role in matricryptin generation not only as the main cellular source of ECM proteins, but also as producers of matrix-degrading proteases. Moreover, several matricryptins exert fibrogenic or reparative actions by modulating fibroblast phenotype and function. This review manuscript focuses on the mechanisms of matricyptin generation in injured and remodeling tissues with an emphasis on fibroblast-matricryptin interactions.

Extracellular Matrix Composition and Remodeling: Current Perspectives on Secondary Palate Formation, Cleft Lip/Palate, and Palatal Reconstruction

Craniofacial development comprises a complex process in humans in which failures or disturbances frequently lead to congenital anomalies. Cleft lip with/without palate (CL/P) is a common congenital anomaly that occurs due to variations in craniofacial development genes, and may occur as part of a syndrome, or more commonly in isolated forms (non-syndromic). The etiology of CL/P is multifactorial with genes, environmental factors, and their potential interactions contributing to the condition. Rehabilitation of CL/P patients requires a multidisciplinary team to perform the multiple surgical, dental, and psychological interventions required throughout the patient's life. Despite progress, lip/palatal reconstruction is still a major treatment challenge. Genetic mutations and polymorphisms in several genes, including extracellular matrix (ECM) genes, soluble factors, and enzymes responsible for ECM remodeling (e.g., metalloproteinases), have been suggested to play a role in the etiology of CL/P; hence, these may be considered likely targets for the development of new preventive and/or therapeutic strategies. In this context, investigations are being conducted on new therapeutic approaches based on tissue bioengineering, associating stem cells with biomaterials, signaling molecules, and innovative technologies. In this review, we discuss the role of genes involved in ECM composition and remodeling during secondary palate formation and pathogenesis and genetic etiology of CL/P. We also discuss potential therapeutic approaches using bioactive molecules and principles of tissue bioengineering for state-of-the-art CL/P repair and palatal reconstruction.

N-Terminomics/TAILS Profiling of Proteases and Their Substrates in Ulcerative Colitis

Dysregulated protease activity is often implicated in the initiation of inflammation and immune cell recruitment in gastrointestinal inflammatory diseases. Using N-terminomics/TAILS (terminal amine isotopic labeling of substrates), we compared proteases, along with their substrates and inhibitors, between colonic mucosal biopsies of healthy patients and those with ulcerative colitis (UC). Among the 1642 N-termini enriched using TAILS, increased endogenous processing of proteins was identified in UC compared to healthy patients. Changes in the reactome pathways for proteins associated with metabolism, adherens junction proteins (E-cadherin, liver-intestinal cadherin, catenin alpha-1, and catenin delta-1), and neutrophil degranulation were identified between the two groups. Increased neutrophil infiltration and distinct proteases observed in ulcerative colitis may result in extensive break down, altered processing, or increased remodeling of adherens junctions and other cellular functions. Analysis of the preferred proteolytic cleavage sites indicated that the majority of proteolytic activity and processing comes from host proteases, but that key microbial proteases may also play a role in maintaining homeostasis. Thus, the identification of distinct proteases and processing of their substrates improves the understanding of dysregulated proteolysis in normal intestinal physiology and ulcerative colitis.

Exploring the extracellular matrix in health and disease using proteomics

The extracellular matrix (ECM) is a complex assembly of hundreds of proteins that constitutes the scaffold of multicellular organisms. In addition to providing architectural and mechanical support to the surrounding cells, it conveys biochemical signals that regulate cellular processes including proliferation and survival, fate determination, and cell migration. Defects in ECM protein assembly, decreased ECM protein production or, on the contrary, excessive ECM accumulation, have been linked to many pathologies including cardiovascular and skeletal diseases, cancers, and fibrosis. The ECM thus represents a potential reservoir of prognostic biomarkers and therapeutic targets. However, our understanding of the global protein composition of the ECM and how it changes during pathological processes has remained limited until recently.

In this mini-review, we provide an overview of the latest methodological advances in sample preparation and mass spectrometry-based proteomics that have permitted the profiling of the ECM of now dozens of normal and diseased tissues, including tumors and fibrotic lesions.

Disrupted type II collagenolysis impairs angiogenesis, delays endochondral ossification and initiates aberrant ossification in mouse limbs

Cartilage remodelling and chondrocyte differentiation are tightly linked to angiogenesis during bone development and endochondral ossification. To investigate whether collagenase-mediated cleavage of the major cartilage collagen (collagen II) plays a role in this process, we generated a knockin mouse in which the mandatory collagenase cleavage site at PQG⁷⁷⁵↓⁷⁷⁶LAG, was mutated to PPG⁷⁷⁵↓⁷⁷⁶MPG (Col2a1^Bailey). This approach blocked collagen II cleavage, and the production of putative collagen II matrikines derived from this site, without modifying matrix metalloproteinase expression or activity. We report here that this mouse (Bailey) is viable. It has a significantly expanded growth plate and exhibits delayed and abnormal angiogenic invasion into the growth plate. Deeper electron microscopy analyses revealed that, at around five weeks of age, a small number of blood vessel(s) penetrate into the growth plate, leading to its abrupt shrinking and the formation of a bony bridge. Our results from in vitro and ex vivo studies suggest that collagen II matrikines stimulate the normal branching of endothelial cells and promote blood vessel invasion at the chondro-osseous junction. The results further suggest that failed collagenolysis in Bailey leads to expansion of the hypertrophic zone and formation of a unique post-hypertrophic zone populated with chondrocytes that re-enter the cell cycle and proliferate. The biological rescue of this in vivo phenotype features the loss of a substantial portion of the growth plate through aberrant ossification, and narrowing of the remaining portion that leads to limb deformation. Together, these data suggest that collagen II matrikines stimulate angiogenesis in skeletal growth and development, revealing novel strategies for stimulating angiogenesis in other contexts such as fracture healing and surgical applications.

Method for Determining Gelatinolytic Activity in Tissue Extracts: Real-Time Gelatin Zymography

To explore the physiological or pathological roles of proteases, it is important to be able to detect and precisely localize them in a tissue, to differentiate between inactive and active forms, as well as to quantify and determine the nature of the enzyme that degrades a given substrate. Here we present a protocol for real-time gelatin zymography that is very useful for the detection of gelatin-degrading proteases in tissue extracts. This method uses fluorescence-labeled gelatin and therefore we also present an easy, fast, and cheap method for labeling gelatin with 2-methoxy-2,4-diphenyl-3(2H)-furanone (MDPF).

A Three-Dimensional Model of Human Lysyl Oxidase, a Cross-Linking Enzyme

Lysyl oxidase (LOX) is a cross-linking enzyme identified 50 years ago, but its 3D structure is still unknown. We have thus built a 3D model of human LOX by homology modeling using the X-ray structure of human lysyl oxidase-like 2 as a template. This model is the first one to recapitulate all known biochemical features of LOX, namely, the coordination of the copper ion and the formation of the lysine tyrosylquinone cofactor and the disulfide bridges. Furthermore, this model is stable during a 1 μs molecular dynamics simulation. The catalytic site is located in a groove surrounded by two loops. The distance between these loops fluctuated during the simulations, which suggests that the groove forms a hinge with a variable opening, which is able to accommodate the various sizes of LOX substrates. This 3D model is a pre-requisite to perform docking experiments with LOX substrates and other partners to identify binding sites and to design new LOX inhibitors specific for therapeutic purpose.

Medicinal Plant Extracts and Their Use As Wound Closure Inducing Agents

Skin insult and damage start a complex healing process that involves a myriad of coordinated reactions at both the cellular and molecular level occurring simultaneously. These processes can be divided into that of cell migration and tissue remodeling of the wound. In addition, it is well known that deep wounds that derive from surgical procedures need a multidisciplinary approach to have a successful wound healing process. Recently, there has been a renowned interest in the identification of active compounds derived from ornamental, edible, and wild plants being used in the cosmetic and skin product industry. Recent reports suggest that active components of several plants such as Propolis and Aloe vera could be used to induce the process of wound healing and tissue regeneration and reducing therefore the time to complete wound closure. Other plant species such as Achillea millefolium or Salvia officinalis have anti-inflammatory properties and promote cellular proliferation contributing to faster tissue regeneration. It has been described that Malva sylvestris influences the formation of fibrosis-free granulation tissue in the skin. Recent observations suggest that Casearia sylvestris induces the angiogenic process. These effects have been evaluated in cell lines, different animal models, and some in randomized clinical trials. In this review we summarize the evidence of plant extracts and their active components (when known) in the acceleration of the wound closure process and tissue repair.

Docking software performance in protein-glycosaminoglycan systems

We present a benchmarking study for protein-glycosaminoglycan systems with eight docking programs: Dock, rDock, ClusPro, PLANTS, HADDOCK, Hex, SwissDock and ATTRACT. We used a non-redundant representative dataset of 28 protein-glycosaminoglycan complexes with experimentally available structures, where a glycosaminoglycan ligand was longer than a trimer. Overall, the ligand binding poses could be correctly predicted in many cases by the tested docking programs, however the ranks of the docking poses are often poorly assigned. Our results suggest that Dock program performs best in terms of the pose placement, has the most suitable scoring function, and its performance did not depend on the ligand size. This suggests that the implementation of the electrostatics as well as the shape complementarity procedure in Dock are the most suitable for docking glycosaminoglycan ligands. We also analyzed how free energy patterns of the benchmarking complexes affect the performance of the evaluated docking software.

Method for Determining Gelatinolytic Activity in Tissue: In Situ Gelatin Zymography

To explore the physiological or pathological roles of proteases, it is important to be able to detect and precisely localize them in a tissue, to differentiate between inactive and active forms, as well as to quantify and determine the nature of the enzyme that degrades a given substrate. Here we present an in situ gelatin zymography method that allows for a precise localization of active gelatin-degrading enzymes in a tissue section. In this method, dye-quenched gelatin is put on top of a tissue section. During an incubation period, active gelatinolytic enzymes will degrade the substrate and fluorescent signals are emitted from the locations of these enzymes.

Matrix remodeling in chronic lung diseases

Multicellular organisms synthesize and renew components of their subcellular and scaffolding proteins, collectively known as the extracellular matrix molecules (ECMs). In the lung, ECMs maintain tensile strength, elasticity, and dictate the specialized function of multiple cell lineages. These functions are critical in lung homeostatic processes including cellular migration and proliferation during morphogenesis or in response to repair. Alterations in lung ECMs that expose cells to new cryptic fragments, generated in response to endogenous proteinases or exogenous toxins, are associated with the development of several common respiratory diseases. How lung ECMs provide or relay vital signals to epithelial and mesenchymal cells has shed new light on development and progression of several common chronic respiratory diseases. This review will consider how ECMs regulate lung homeostasis and their reorganization under pathological conditions that can modulate the inflammatory diseases asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). Better understanding of changes in the distribution of lung ECM could provide novel therapeutic approaches to treat chronic lung diseases.

Matrix modeling and remodeling: A biological interplay regulating tissue homeostasis and diseases

The overall structure and architecture of the extracellular matrix undergo dramatic alterations in composition, form, and functionality over time. The stochasticity begins during development, essential for maintaining organismal homeostasis and is heavily implicated in many pathobiological states including fibrosis and cancer. Modeling and remodeling of the matrix is driven by the local cellular milieu and secreted and cell-associated components in a framework of dynamic reciprocity. This collection of expertly-written reviews aims to relay state-of-the-art information concerning the mechanisms of matrix modeling and remodeling in physiological development and disease.

Insights into the structure and dynamics of lysyl oxidase propeptide, a flexible protein with numerous partners

Lysyl oxidase (LOX) catalyzes the oxidative deamination of lysine and hydroxylysine residues in collagens and elastin, which is the first step of the cross-linking of these extracellular matrix proteins. It is secreted as a proenzyme activated by bone morphogenetic protein-1, which releases the LOX catalytic domain and its bioactive N-terminal propeptide. We characterized the recombinant human propeptide by circular dichroism, dynamic light scattering, and small-angle X-ray scattering (SAXS), and showed that it is elongated, monomeric, disordered and flexible (D_max: 11.7 nm, R_g: 3.7 nm). We generated 3D models of the propeptide by coarse-grained molecular dynamics simulations restrained by SAXS data, which were used for docking experiments. Furthermore, we have identified 17 new binding partners of the propeptide by label-free assays. They include four glycosaminoglycans (hyaluronan, chondroitin, dermatan and heparan sulfate), collagen I, cross-linking and proteolytic enzymes (lysyl oxidase-like 2, transglutaminase-2, matrix metalloproteinase-2), a proteoglycan (fibromodulin), one growth factor (Epidermal Growth Factor, EGF), and one membrane protein (tumor endothelial marker-8). This suggests new roles for the propeptide in EGF signaling pathway.

The selectivity of galardin and an azasugar-based hydroxamate compound for human matrix metalloproteases and bacterial metalloproteases

Inhibitors targeting bacterial enzymes should not interfere with enzymes of the host, and knowledge about structural determinants for selectivity is important for designing inhibitors with a therapeutic potential. We have determined the binding strengths of two hydroxamate compounds, galardin and compound 1b for the bacterial zinc metalloproteases, thermolysin, pseudolysin and auerolysin, known to be bacterial virulence factors, and the two human zinc metalloproteases MMP-9 and MMP-14. The active sites of the bacterial and human enzymes have huge similarities. In addition, we also studied the enzyme-inhibitor interactions by molecular modelling. The obtained Ki values of galardin for MMP-9 and MMP-14 and compound 1b for MMP-9 are approximately ten times lower than previously reported. Compound 1b binds stronger than galardin to both MMP-9 and MMP-14, and docking studies indicated that the diphenyl ether moiety of compound 1b obtains more favourable interactions within the S´1-subpocket than the 4-methylpentanoyl moiety of galardin. Both compounds bind stronger to MMP-9 than to MMP-14, which appears to be due to a larger S´1-subpocket in the former enzyme. Galardin, but not 1b, inhibits the bacterial enzymes, but the galardin Ki values were much larger than for the MMPs. The docking indicates that the S´1-subpockets of the bacterial proteases are too small to accommodate the diphenyl ether moiety of 1b, while the 4-methylpentanoyl moiety of galardin enters the pocket. The present study indicates that the size and shape of the ligand structural moiety entering the S´1-subpocket is an important determinant for selectivity between the studied MMPs and bacterial MPs.

New Insights into the Role of Basement Membrane-Derived Matricryptins in the Heart

The extracellular matrix (ECM), which contributes to structural homeostasis as well as to the regulation of cellular function, is enzymatically cleaved by proteases, such as matrix metalloproteinases and cathepsins, in the normal and diseased heart. During the past two decades, matricryptins have been defined as fragments of ECM with a biologically active cryptic site, namely the 'matricryptic site,' and their biological activities have been initially identified and clarified, including anti-angiogenic and anti-tumor effects. Thus, matricryptins are expected to be novel anti-tumor drugs, and thus widely investigated. Although there are a smaller number of studies on the expression and function of matricryptins in fields other than cancer research, some matricryptins have been recently clarified to have biological functions beyond an anti-angiogenic effect in heart. This review particularly focuses on the expression and function of basement membrane-derived matricryptins, including arresten, canstatin, tumstatin, endostatin and endorepellin, during cardiac diseases leading to heart failure such as cardiac hypertrophy and myocardial infarction.

Insights into the key roles of epigenetics in matrix macromolecules-associated wound healing

Extracellular matrix (ECM) is a dynamic network of macromolecules, playing a regulatory role in cell functions, tissue regeneration and remodeling. Wound healing is a tissue repair process necessary for the maintenance of the functionality of tissues and organs. This highly orchestrated process is divided into four temporally overlapping phases, including hemostasis, inflammation, proliferation and tissue remodeling. The dynamic interplay between ECM and resident cells exerts its critical role in many aspects of wound healing, including cell proliferation, migration, differentiation, survival, matrix degradation and biosynthesis. Several epigenetic regulatory factors, such as the endogenous non-coding microRNAs (miRNAs), are the drivers of the wound healing response. microRNAs have pivotal roles in regulating ECM composition during wound healing and dermal regeneration. Their expression is associated with the distinct phases of wound healing and they serve as target biomarkers and targets for systematic regulation of wound repair. In this article we critically present the importance of epigenetics with particular emphasis on miRNAs regulating ECM components (i.e. glycoproteins, proteoglycans and matrix proteases) that are key players in wound healing. The clinical relevance of miRNA targeting as well as the delivery strategies designed for clinical applications are also presented and discussed.

The Multimerization State of the Amyloid-β42 Amyloid Peptide Governs its Interaction Network with the Extracellular Matrix

The goals of this work were i) to identify the interactions of amyloid-β (Aβ)42 under monomeric, oligomeric, and fibrillar forms with the extracellular matrix (ECM) and receptors, ii) to determine the influence of Aβ42 supramolecular organization on these interactions, and iii) to identify the molecular functions, biological processes, and pathways targeted by Aβ42 in the ECM. The ECM and cell surface partners of Aβ42 and its supramolecular forms were identified with protein and glycosaminoglycan (GAG) arrays (81 molecules in triplicate) probed by surface plasmon resonance imaging. The number of partners of Aβ42 increased upon its multimerization, ranging from 4 for the peptide up to 53 for the fibrillar aggregates. The peptide interacted only with ECM proteins but their percentage among Aβ42 partners decreased upon multimerization. Aβ42 and its supramolecular forms recognized different molecular features on their partners, and the partners of Aβ42 fibrillar forms were enriched in laminin IV-A, N-terminal, and EGF-like domains. Aβ42 oligomerization triggered interactions with receptors, whereas Aβ42 fibrillogenesis promoted binding to GAGs, proteoglycans, enzymes, and growth factors and the ability to interact with perineuronal nets. Fibril aggregation bind to further membrane proteins including tumor endothelial marker-8, syndecan-4, and discoidin-domain receptor-2. The partners of the Aβ42 supramolecular forms are enriched in proteins contributing to cell growth and/or maintenance, involved in integrin cell surface interactions and expressed in kidney cancer, preadipocytes, and dentin. In conclusion, the supramolecular assembly of Aβ42 governs its ability to interact in vitro with ECM proteins, remodeling and crosslinking ECM enzymes, proteoglycans, and receptors.

Proteinases and their receptors in inflammatory arthritis: an overview

Proteinases are enzymes with established roles in physiological and pathological processes such as digestion and the homeostasis, destruction and repair of tissues. Over the past few years, the hormone-like properties of circulating proteinases have become increasingly appreciated. Some proteolytic enzymes trigger cell signalling via proteinase-activated receptors, a family of G protein-coupled receptors that have been implicated in inflammation and pain in inflammatory arthritis. Proteinases can also regulate ion flux owing to the cross-sensitization of transient receptor potential cation channel subfamily V members 1 and 4, which are associated with mechanosensing and pain. In this Review, the idea that proteinases have the potential to orchestrate inflammatory signals by interacting with receptors on cells within the synovial microenvironment of an inflamed joint is revisited in three arthritic diseases: osteoarthritis, spondyloarthritis and rheumatoid arthritis. Unanswered questions are highlighted and the therapeutic potential of modulating this proteinase-receptor axis for the management of disease in patients with these types of arthritis is also discussed.

Stromal Versican Regulates Tumor Growth by Promoting Angiogenesis

The proteoglycan versican is implicated in growth and metastases of several cancers. Here we investigated a potential contribution of stromal versican to tumor growth and angiogenesis. We initially determined versican expression by several cancer cell lines. Among these, MDA-MB231 and B16F10 had none to minimal expression in contrast to Lewis lung carcinoma (LLC). Notably, tumors arising from these cell lines had higher versican levels than the cell lines themselves suggesting a contribution from the host-derived tumor stroma. In LLC-derived tumors, both the tumor and stroma expressed versican at high levels. Thus, tumor stroma can make a significant contribution to tumor versican content. Versican localized preferentially to the vicinity of tumor vasculature and macrophages in the tumor. However, an ADAMTS protease-generated versican fragment uniquely localized to vascular endothelium. To specifically determine the impact of host/stroma-derived versican we therefore compared growth of tumors from B16F10 cells, which produced littleversican, in Vcan ^hdf/+ mice and wild-type littermates. Tumors in Vcan ^hdf/+ mice had reduced growth with a lower capillary density and accumulation of capillaries at the tumor periphery. These findings illustrate the variability of tumor cell line expression of versican, and demonstrate that versican is consistently contributed by the stromal tissue, where it contributes to tumor angiogenesis.

Fragments generated upon extracellular matrix remodeling: Biological regulators and potential drugs

The remodeling of the extracellular matrix (ECM) by several protease families releases a number of bioactive fragments, which regulate numerous biological processes such as autophagy, angiogenesis, adipogenesis, fibrosis, tumor growth, metastasis and wound healing. We review here the proteases which generate bioactive ECM fragments, their ECM substrates, the major bioactive ECM fragments, together with their biological properties and their receptors. The translation of ECM fragments into drugs is challenging and would take advantage of an integrative approach to optimize the design of pre-clinical and clinical studies. This could be done by building the contextualized interaction network of the ECM fragment repertoire including their parent proteins, remodeling proteinases, and their receptors, and by using mathematical disease models.

Multifaceted Roles of Metzincins in CNS Physiology and Pathology: From Synaptic Plasticity and Cognition to Neurodegenerative Disorders

The extracellular matrix (ECM) and membrane proteolysis play a key role in structural and functional synaptic plasticity associated with development and learning. A growing body of evidence underscores the multifaceted role of members of the metzincin superfamily, including metalloproteinases (MMPs), A Disintegrin and Metalloproteinases (ADAMs), A Disintegrin and Metalloproteinase with Thrombospondin Motifs (ADAMTSs) and astacins in physiological and pathological processes in the central nervous system (CNS). The expression and activity of metzincins are strictly controlled at different levels (e.g., through the regulation of translation, limited activation in the extracellular space, the binding of endogenous inhibitors and interactions with other proteins). Thus, unsurprising is that the dysregulation of proteolytic activity, especially the greater expression and activation of metzincins, is associated with neurodegenerative disorders that are considered synaptopathies, especially Alzheimer's disease (AD). We review current knowledge of the functions of metzincins in the development of AD, mainly the proteolytic processing of amyloid precursor protein, the degradation of amyloid β (Aβ) peptide and several pathways for Aβ clearance across brain barriers (i.e., blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB)) that contain specific receptors that mediate the uptake of Aβ peptide. Controlling the proteolytic activity of metzincins in Aβ-induced pathological changes in AD patients' brains may be a promising therapeutic strategy.

Urinary extracellular vesicles. A promising shortcut to novel biomarker discoveries

Proteomic and genomic techniques have reached full maturity and are providing unforeseen details for the comprehensive understanding of disease pathologies at a fraction of previous costs. However, for kidney diseases, many gaps in such information remain to inhibit major advances in the prevention, treatment and diagnostics of these devastating diseases, which have enormous global impact. The discovery of ubiquitous extracellular vesicles (EV) in all bodily fluids is rapidly increasing the fundamental knowledge of disease mechanisms and the ways in which cells communicate with distant locations in processes of cancer spread, immunological regulation, barrier functions and general modulation of cellular activity. In this review, we describe some of the most prominent research streams and findings utilizing urinary extracellular vesicles as highly versatile and dynamic tools with their extraordinary protein and small regulatory RNA species. While being a highly promising approach, the relatively young field of EV research suffers from a lack of adherence to strict standardization and carefully scrutinized methods for obtaining fully reproducible results. With the appropriate guidelines and standardization achieved, urine is foreseen as forming a unique, robust and easy route for determining accurate and personalized disease signatures and as providing highly useful early biomarkers of the disease pathology of the kidney and beyond.

Activity-dependent proteolytic cleavage of cell adhesion molecules regulates excitatory synaptic development and function

Activity-dependent remodeling of neuronal connections is critical to nervous system development and function. These processes rely on the ability of synapses to detect neuronal activity and translate it into the appropriate molecular signals. One way to convert neuronal activity into downstream signaling is the proteolytic cleavage of cell adhesion molecules (CAMs). Here we review studies demonstrating the mechanisms by which proteolytic processing of CAMs direct the structural and functional remodeling of excitatory glutamatergic synapses during development and plasticity. Specifically, we examine how extracellular proteolytic cleavage of CAMs switches on or off molecular signals to 1) permit, drive, or restrict synaptic maturation during development and 2) strengthen or weaken synapses during adult plasticity. We will also examine emerging studies linking improper activity-dependent proteolytic processing of CAMs to neurological disorders such as schizophrenia, brain tumors, and Alzheimer's disease. Together these findings suggest that the regulation of activity-dependent proteolytic cleavage of CAMs is vital to proper brain development and lifelong function.

The biology of meniscal pathology in osteoarthritis and its contribution to joint disease: beyond simple mechanics

The meniscal cartilages in the knee function to improve congruity of the medial and lateral femoro-tibial joints and play critical roles in load distribution and joint stability. Meniscal tears of various configurations are one of the most common conditions of the knee and are associated with an increased risk of developing osteoarthritis (OA). While this risk has been largely attributed to loss of the biomechanical functions of the menisci, there is accumulating evidence suggesting that other aspects of meniscal biology may play a role in determining the long-term consequences of meniscal damage for joint health. In this narrative review, we examine the existing literature and present some new data implicating synthesis and secretion of enzymes and other pro-catabolic mediators by injured and degenerate menisci, contributing to the pathological change in other knee joint tissues in OA.